In-situ microscope device reactors

ABSTRACT

An in-situ microscope device for reactors, especially bioreactors, having an immersion tube in a reactor connecting port, which, inside the reactor, has an inlet for a sample area, also a microscope outer tube, which is coaxially placed inside the immersion tube and which, on the inner end with the objective, is directed toward the sample area that is located between an objective cover glass and an object support glass body arranged opposite the same. The exterior of the microscope outer tube is connected to a camera for recording the image of the sample area. Also included is a rinsing chamber having closeable openings, through which cleaning agents can be introduced, is connected to the exterior of the reactor connecting port, and that the immersion tube can move in an axial direction inside the connecting port and can be retracted until the inlet is in contact with the rinsing chamber in order to enable a cleaning of the sample area.

The present invention relates to an in-situ microscope device forreactors, such as for example bioreactors.

BACKGROUND OF THE INVENTION

With such in-situ microscope devices, examinations can be carried out onspecimens of the material in the inside of the reactor during ongoingoperation, for example the concentration of particular cells in themedium can be monitored. The basic principles of in-situ microscopy forreactors are described in patent specification DE 40 32 002 C2.

An in-situ microscope device with the features of the precharacterizingclause of claim 1 is described e.g. in the dissertation“In-situ-Mikroskopie; Ein neues Verfahren zur Online-Bestimmung derBiomasse bei Kultivierungsprozessen” [In-situ microscopy: a new processfor online determination of biomass in cultivation processes], Dr.Christoph Bittner, Hanover, 1994.

The monitoring and controlling of biotechnological processes has gaineda major significance in the recent past e.g. in the chemical andpharmaceutical industries. Examples of this are the synthesis of humanproteins, such as e.g. interleukin (IL-2), tissue plasminogen activator(t-PA) or antithrombin (AT-III), the preparation of which with the helpof organic synthesis can be achieved only with difficulty, with theresult that the manufacture of these proteins with the help of thecultivation of mammal cells is preferred. Microorganisms, here inparticular yeasts, are used also in the manufacture of products of thefood industry, e.g. beer, wine, cheese or bread. Further products orpharmaceuticals are produced by the cultivation of other organisms. Inthe case of in-situ microscopy, a microscope probe is inserted into aconnection port of a fermenter (reactor) in order to monitor and controlsuch processes. This microscope probe enables an image to bephotographed directly in the culture stock. The photographed microscopeimage is photographed and digitized by a CCD camera connected to thein-situ microscope. The evaluation of the digitized microscopic imagesis carried out with the help of image-processing programs on a standardcomputer. Information about cell sizes and biomass, cell-sizedistribution, cell concentration, cell morphology and cell vitality canbe obtained using the image data material obtained with the in-situmicroscope and analyses applied to it. On the basis of the information,thereby obtained during ongoing operation, about the state of the systemlocated in the reactor, process parameters can be influenced andcontrolled in order to achieve a desired development of the system.

An in-situ microscope for the observation of cultivation processes inyeasts is described in the above-mentioned dissertation by Bittner. Themicroscope has a dip tube which is inserted into a reactor connectionport. In the end-section of the dip tube lying in the inside of thereactor, an inlet is provided through which the culture medium can flowfreely. A microscope external tube is arranged coaxially in the dip tubeand, with its lens lying at the inner end, is directed towards aspecimen zone which is defined between the cover glass of the lens and aslide glass body lying opposite. Connected to the opposite end is themicroscope external tube with a camera for photographing the image ofthe specimen zone. If the specimen zone is open, the lens cover glassand the slide glass body lying opposite lie at some distance from eachother, the culture medium from the inside of the reactor being able toflow freely through this space. In order to photograph the image, thespecimen zone is closed by moving the slide glass body onto the lenscover glass until a sealing ring surrounding the slide glass body comesto rest against the lens cover glass and thus creates a specimen zonewith a defined volume between the slide glass body and the lens coverglass. In the known device, the specimen zone is closed by pulling theslide glass body with an illumination unit below it against the lens.This movement is achieved via a pull rod which runs in longitudinaldirection in the dip tube alongside the microscope external tube, and isconnected at one end to the unit of the slide glass body and at theother end to a drive outside the dip tube. Furthermore, a wipingapparatus is provided with which the lens cover glass is intended to becleaned by wiping off if required. Such a wiping apparatus is necessaryas the glass rapidly becomes dirty and another cleaning method cannot becarried out at all while cultivation is in progress and, even after thecultivation process is stopped, can be carried out only if considerableeffort is expended and the microscope is completely removed from thereactor. The wiper is also driven by an external drive via a mechanicalpower transmission means.

The known in-situ microscope device is disadvantageous in variousrespects. For example, it is disadvantageous that mechanical powertransmission means alongside the microscope tube must be guided throughthe dip tube, as this restricts the space available for the microscopetube. Furthermore, such mechanical power transmission means are costlyin design terms and are incident-prone.

However, the main disadvantage of the known in-situ microscope devicesis that the microscope is not accessible while cultivation is inprogress because, if the reactor is opened by removing the dip tube orby pulling out the microscope, the cultivation would be contaminated.Furthermore, if the microscope was installed at the side, the reactorwould first have to be emptied, which for practical use is out of thequestion.

The removability of the microscope is of significance not only forcleaning purposes during the operation, but also for thesterilization/autoclaving of the reactor system before commissioning, astemperatures of over 120° C. are used.

For industrial-scale applications of in-situ microscopy, microscopedevices are required which are robust, flexible and easy to handle.

The object of the present invention is therefore to create an in-situmicroscope device, the sensitive parts of which are accessible at anytime, without having to interrupt the cultivation process or endangeringit through a contamination.

The characterizing features of patent claim 1 in conjunction with itsprecharacterizing clause serve to achieve this object. Advantageousversions of the invention are listed in the dependent claims.

BRIEF DESCRIPTION OF THE INVENTION

According to the invention, it is provided that the dip tube is guidedmovable in axial direction in the reactor connection port, to which arinsing chamber with sealable openings is externally connected, throughwhich cleaning agents can be fed in. The dip tube can be pulled backinto the connection port until the inlet of the dip tube communicateswith the rinsing chamber. Sealing means are provided at the dip tube inorder to keep the internal space of the reactor sealed off from therinsing chamber when the dip tube is pulled back into the rinsingchamber. In this way, the specimen zone can be cleaned, when the diptube is pulled back into the rinsing chamber, by feeding cleaning agentsinto the rinsing chamber. The internal space of the reactor remainssealed off from the inside of the rinsing chamber in order that thespecimen zone can also be cleaned while cultivation is in progress,without the danger of contamination.

Furthermore, the microscope external tube can be pulled out when the diptube is pulled back into the rinsing chamber. Thereby, all parts of themicroscope device which are arranged inside the dip tube can be removedand if necessary replaced or repaired, without the sterile barrier tothe inside of the reactor being broken through. Thereby, changes to thedesign and fitting of the microscope, maintenance work and the like canalso be carried out during ongoing operation of the reactor, without thecultivation process in the reactor having to be interrupted, or thedanger(of contamination. Thereby, handling during ongoing operation,operational reliability and variability can be decisively improved byreplacing components of the microscope, with the result that the in-situmicroscope device is particularly well-suited to industrial applicationsdue to its flexibility and robustness.

In an advantageous version, there is accommodated in the end of the diptube pointing towards the inside of the reactor an illumination unitwhich carries the slide glass body and has a light source in order toilluminate the specimen zone through the slide glass body.

In an advantageous version, the microscope external tube is for its parthoused in a microscope-housing tube, wherein the microscope-housing tubeis closed at the end facing the inside of the reactor except for aninlet for specimen material and surrounds the specimen zone from therear, and wherein the illumination unit is arranged at the inward-lyingend of the microscope-housing tube. The microscope external tube isadvantageously housed movable in axial direction in themicroscope-housing tube and a drive is provided which acts on theoutward-lying end of the microscope external tube. The microscopeexternal tube can be moved relative to the microscope-housing tube bythe drive, in order thus to be able to open and close the specimen zonebetween the lens cover glass at the microscope external tube and theslide glass body of the illumination unit by pushing forward and pullingback the microscope external tube controlled by the drive.Alternatively, at the inner end of the microscope-housing tube a drivecan be provided which acts on the illumination unit housed movable inaxial direction in the microscope-housing tube, in order to be able toopen and close the specimen zone by moving the illumination unit.Particularly advantageously, a step motor or a regulated direct-currentmotor is used as a drive, whereby a very precise setting of the specimenzone can be achieved.

In an alternative version, the illumination unit and the microscopeexternal tube form two separate units which are not housed as above in acommon microscope-housing tube, the illumination unit being arranged atthe inner end of the dip tube and the microscope external tube beinghoused movable in axial direction directly in the dip tube, themicroscope-housing tube in the version described above thus beingdispensed with. Furthermore, a drive is provided which acts on the end,lying outside the reactor, of the microscope external tube in order tomove this relative to the dip tube in a controlled manner, in order thusto be able to open and close the specimen zone between the lens coverglass at the microscope external tube and the slide glass body of theillumination unit by pushing forward and pulling back the microscopeexternal tube.

In all versions, it can be provided that a microscope tube is housedmovable in the microscope external tube and that a drive means isprovided in order to be able to move the microscope tube in longitudinaldirection in a controlled manner, in order thus to be able to set thelens against the microscope tube relative to the specimen zone forfocusing.

With the previously described forms, it is possible to exploit thecross-section available in the dip tube as far as possible, because nodrive transmissions need to be guided through the dip tube. Furthermore,the position of the slide glass body and the lens cover glass relativeto each other, which between them form the specimen zone, can be setvery accurately in a controlled manner by the drive.

The fact that the cross-section area of the dip tube can be fullyexploited, because no drive transmissions need to be guided through,means that dip tubes with a relatively small internal diameter, intowhich a microscope external tube is introduced, can also be used. Inthis way, dip tubes of conventional, standardized exchangeable probesystems, in which the external diameter of the probe to be used islimited, can also be used.

If the dip tube is pulled back into the rinsing chamber, cleaningagents, e.g. superheated steam, can be fed in through the sealableopenings of the rinsing chamber in order that in this way the cleaningagents enter the specimen zone through the inlet of the dip tube, inorder to clean the specimen zone. If the dip tube is pulled back untilits inlet communicates with the rinsing chamber, the inside of thereactor is sealed off and the inlet of the dip tube lies in the insideof the rinsing chamber and no longer communicates with the inside of thereactor. In this situation, the microscope external tube or themicroscope-housing tube can be pulled out of the dip tube. All essentialparts of the microscope are thereby accessible and can be repaired orvaried by replacing components. The last-mentioned possibility ofchanging the properties of the microscope by replacing components alsoapplies to the specimen zone, because e.g. the slide glass body can bereplaced in order to obtain another geometric definition of the specimenzone.

If a drive is provided in order to set the specimen zone by moving themicroscope external tube or the illumination unit relative to eachother, an accurate definition of the specimen zone is possible throughsuch a precisely controllable drive. The motor control allows a variableconfiguration of the specimen zone, i.e. the height of the specimen zoneto be selected through variable approaching. A supplementary oralternative option of a variable configuration of the specimen zone isoffered by particular forms of the slide glass body which are describedin the following.

In this regard, it is preferred in particular that the slide glass bodyhas a sapphire glass plate with a level external area, on thecircumference of which an annular rim of a predefined thickness isformed which serves as a spacer if the lens cover glass is moved againstthe slide glass body until it rests against the annular rim in order toclose the specimen zone. By keeping ready slide glass bodies withannular rims of various thicknesses, the height of the specimen zone canbe varied by using a selected slide glass body. The annular rim can beformed e.g. by the polishing in of a recess into a sapphire glass plateor produced by applying an annular material layer.

Instead of an annular spacer, several discrete spacer bodies can also beformed on the sapphire glass plate, e.g. two oblong spacers whichbetween them form a channel-shaped recess open at both sides. Inversions in which several discrete spacers are provided at a distancefrom each other on the slide glass body, the specimen zone is open atthe side opposite the surrounding medium in order that cells can flowcontinuously through the specimen zone and therefore the image recordedby the microscope continuously changes. A higher measuring frequency canthus be achieved by the photographing of image sequences because thespecimen zone need not be opened and closed for each image, rather acomplete replacement of the medium in the specimen zone should beeffected by the opening of this only at certain intervals. This versionof the specimen zone differs significantly from the specimen zonesclosed on all sides, which serve exclusively to keep the specimen steadyin the specimen zone. The opposite is the case in the variant proposedhere. When using LEDs of high light intensity for illumination, theexposure time of the camera can be shortened such that the cells arerepresented sharply despite their movement.

The in-situ microscope device according to the invention can operatewith a finite or an infinite lens.

Furthermore, in addition to the already-described operating method oftransillumination bright-field microscopy, the in-situ microscope devicecan also be used with an illumination unit below the specimen zone fordirect-light darkfield microscopy or for direct-light bright-fieldmicroscopy.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in the following with reference to anembodiment in the drawings in which:

FIG. 1 shows a partial-section view of an in-situ microscope device inoperating position in the reactor (above) and in pulled-back position(below) of the dip tube in the reactor connection port, themicroscope-housing tube being removed from the dip tube in the lowerrepresentation;

FIG. 2 shows a partial-section view of the version from FIG. 1, themicroscope external tube being represented arranged in themicroscope-housing tube;

FIG. 3 shows a sectional representation of an alternative version of thein-situ microscope including an enlarged sectional representation of anillumination unit;

FIG. 4 represents various versions of a slide glass body.

DETAILED DESCRIPTION OF THE INVENTION

The version of the in-situ microscope device represented schematicallyin section in the FIGS. 1 and 2 has a dip tube 2 which is inserted intoa reactor connection port 6 which is firmly connected to the reactorwall (not shown). In FIG. 2, in order to simplify the representation,the rinsing chamber 7 against the reactor connection port 6 is notshown. In the position represented above in FIG. 1, the dip tube 2 withits inlet 4 lies inside the reactor in order that the medium in theinside of the reactor can flow through the inlet 4 through the specimenzone of the in-situ microscope device. Connected outside to the reactorconnection port 6 is a rinsing chamber 7 which rests at its external endwith seals against the outer surface of the dip tube 2. The dip tube 2can be pulled back through the reactor connection port 6 until the inlet4 communicates with the rinsing chamber 7, as represented in FIG. 1below. In this position, seals 9 running round outside at thecircumference, which rest against the inner wall of the reactorconnection port, seal off the inside of the reactor so that there is nolonger a connection between the inlet 4 of the dip tube and the insideof the reactor. Cleaning agents, e.g. superheated steam, can be fed inthrough the sealable openings 8 of the rinsing chamber 7 in order toclean the specimen zone.

The microscope-housing tube 20 is housed movable in the dip tube. In theposition represented below in FIG. 1, the microscope-housing tube isremoved from the dip tube with the result that all parts of themicroscope located therein can be handled for maintenance or for thereplacement of components. At the same time, the inside of the reactoris sealed off by the dip tube 2 in the connection port 6 with the resultthat the inside of the reactor cannot be contaminated and thecultivation process can continue.

As represented in FIG. 2, there is located in the microscope-housingtube 20 a microscope external tube 10 which is housed movable therein.The microscope-housing tube 20 likewise has an inlet which communicateswith the inlet 4 of the dip tube with the result that the medium in theinside of the reactor can flow through the specimen zone 12.

Outside the reactor a drive 30 is provided, e.g. a step motor, whichprovides a drive between microscope-housing tube 20 and microscopeexternal tube 10 in order to move the latter relative to themicroscope-housing tube. Through the movability of the microscopeexternal tube 10, in this version the movement is realized which is usedto open and close the specimen zone, the specimen zone being definedbetween a slide glass body which during operation is arranged fixed inthe lower section of the dip tube, and the lens cover glass which isarranged at the end of the movable microscope external tube 10. Throughthe movable housing of the microscope external tube 10 and the provisionof a drive 30 in order to move the microscope external tube 10 so as toopen and close the specimen zone, the cross-section area in themicroscope-housing tube 20 can be fully exploited for the microscopeexternal tube 10, because no mechanical drive transmissions whatsoeverinto the front section of the specimen zone are required.

The drive 30 engages on one side at a pusher of the microscope-housingtube 20 and on the other side at a pusher of the microscope externaltube 10 in order to move these relative to each other. The size of thespecimen zone, i.e. the distance between the slide glass body at theillumination unit and the lens cover glass at the microscope externaltube 10, is defined by the position of the microscope external tube 10relative to the microscope-housing tube 20.

As a drive 30 a step motor is preferably used, which opens up thepossibility of being able to precisely adapt the specimen zone withvariable height to the respective requirements in a specific situation.However, in principle any drive means is possible for the drive 30, thuse.g. pneumatic drive means or a piezomodule can also be used for thedrive 30. The motor control allows the specimen zone to be set in avariable manner, i.e. the height of the specimen zone to be selectedthrough variable approaching. A further possibility of realizingvariable specimen zones consists of providing slide glass bodies withselected spacers which define the distance from the lens cover glass, asdescribed further below in connection with FIG. 4.

At the outer end, the microscope external tube 10 is connected to acamera 31, e.g. a CCD camera, which records the microscope image of thespecimen zone.

The version represented in FIGS. 1 and 2 has the advantage that bypulling out the microscope-housing tube 20 the whole microscope can beremoved as a unit from the dip tube if the dip tube is pulled back intothe position represented below in FIG. 1, without adversely affectingthe sterile conditions in the inside of the reactor, because the insideof the reactor is kept sealed off by the inner end of the dip tube andthe seals 9, 9′.

Located in the microscope-housing tube below the specimen zone 12 (FIG.2) is an illumination unit which has a light source, if necessarylenses, and the slide glass body at the end facing towards the specimenzone 12.

FIG. 3 shows a partial view of a further version in section, only thedip tube 2 with the lens end of the microscope external tube 10 insertedtherein being represented here, while the reactor connection port andthe rinsing chamber are omitted in order to simplify the representation.There is no microscope-housing tube in this version. Instead of this,the illumination unit and the microscope external tube 10 are houseddirectly in the dip tube 2. The illumination unit is located in the endof the dip tube lying in the inside of the reactor and is keptdetachable by a magnet 18 at the base of the dip tube. The illuminationunit has a contact body housed movable therein, which rests on themagnet 18. The movable contact is in contact with a switch 19 in theinside of the illumination unit. The switch 19 is connected to a powersource, e.g. an accumulator, and connects the power source to the lightsource when the switch is triggered, preferably to a light-emittingdiode (LED). Above the light source lies a condenser 17 and above this aslide glass body 16 which is designed as a sapphire plate.

If the specimen zone 12 is closed, the microscope external tube 10 ismoved towards the illumination unit by a drive until the lens coverglass 14 comes into contact with points provided for this on the slideglass body 16. Thereby the illumination unit as a whole is pressedtowards the base of the dip tube, whereby the movable contact body actson the switch 19 and the light source is activated if the specimen zone12 is closed. As the light source is switched on only if the specimenzone 12 is closed, power consumption is minimal. The fixing of theillumination unit to the base of the dip tube 2 by a securing apparatus,e.g. a magnet, is important in order that the illumination unit does notdetach itself from the base if the specimen zone 12 is opened (thiscould otherwise occur due to adhesive forces which act between the lenscover glass 14 and the slide glass body 16 and the liquid film enclosedby these). The illumination unit is provided with recesses at its endfacing the specimen zone in order that they do not completely fill thecross-section of the dip tube 2 there. As a result of these recesses,the illumination unit can be grasped with a special tool, for exampletongs, and removed from the dip tube 2 if the dip tube 2 is in thepulled-back position in the reactor connection port and the rinsingchamber, and the microscope external tube 10 is pulled out of the diptube 2.

As a result of the invention, it is possible during the ongoingcultivation process to pull back the dip tube into the reactorconnection port and to remove the microscope components, whereby inparticular the specimen zone can be varied by replacing components, e.g.the slide glass body.

In FIG. 3, the slide glass body 16 is merely represented schematicallyas a sapphire glass plate. For an exactly defined specimen zone to beformed between the lens cover glass 14, the outer surface of which islevel, and the surface of the slide glass body 16, the slide glass body16 can be provided on its outer surface with spacers which come to restagainst the lens cover glass 14 if the specimen zone is closed, with theresult that an intermediate layer of a defined thickness is formed.

In order to realize such spacers, e.g. an annular structure can bemounted on the plate-shaped slide glass body, wherein this ring bodyshould be formed from biocompatible material and should not becompressible.

In FIG. 4, such a ring body has the reference number 32. Such a ringbody 32 of a predefined thickness can be formed e.g. by evaporatingmaterial onto the sapphire glass plate 33. The ring body 32 can also beformed by the polishing in of a recess. Furthermore, the ring body canalso be cut out from high-grade steel foils or plastic foils and mountedon the glass plate. In principle, it is also possible to form the ringby evaporating sapphire onto the sapphire glass plate 33. In all cases,the ring body 32 can be formed with a predefined thickness with theresult that a specimen zone of a predefined height is defined which isdetermined as a spacer by the thickness of the ring body 32. Thereby anyheight of specimen zone can be predefined, and this height can bechanged relatively easily (by replacing the ring body) or by completelyreplacing the slide glass body.

The method of manufacturing an external ring body by the polishing in ofa recess is more economical than evaporation, but is less accurate.Furthermore, during the polishing in of the recess, scratches can occurwhich can disrupt the photographing of the image. In typical cases, therecess is formed with a depth of 40 μm.

In the case of the prescribed specimen zones with an external ring bodyas a spacer, the volume of the specimen zone is closed off from thesurrounding culture medium if the lens cover glass is brought up,because the lens cover glass rests against the ring body and this isclosed at the circumference. In this way, the medium is kept steady inthe specimen zone.

In another form of the specimen zone, this can be defined by a pluralityof separate spacers 34 or 35, as represented below in FIG. 4. E.g. tworectilinear spacers 34 can be provided which between themselves enclosea channel-shaped zone above the surface of the slide glass body 33, theends of the channel-shaped zone being open. In this way, if the lenscover glass comes to rest against the rectilinear spacers 34, an openspecimen zone is formed. The cells of the culture medium can flowthrough this open specimen zone. The composition of the specimen-zonecontent therefore changes constantly. The same applies to versions withseveral spacers 35 which are arranged at the circumference of a ring onthe sapphire glass plate 33, but have several breaks with the resultthat the specimen zone is likewise designed to be open.

By photographing image sequences in open specimen zones a much highermeasuring frequency can be realized, which can be of significance whenmeasuring rapidly-growing organisms. The higher measuring frequency ispossible because the specimen zone need not be opened and closed forevery image in the sequence, rather a complete replacement of thecontents of the specimen zone is carried out by opening and closing thespecimen zone only after specific longer periods. This version of thespecimen zone clearly differs from the previously-described specimenzones which serve exclusively to keep the cells in the specimen zonesteady. In the case of the open specimen zones, the opposite is achievedand this enables a constant flow through the specimen zone to bemaintained in order to avoid blockages or deposits and to guaranteerepresentative specimens. When using light sources of high lightintensity, the exposure time of the CCD camera can be shortened to theextent that the cells are represented sharply despite the movement.

In all versions of the invention, a microscope tube which carries thelens at its front end can be housed movable within a microscope externaltube 10, with the result that the microscope tube can be moved and setrelative to the lens cover glass 14 on the microscope external tube 10by drive means, in order thereby to enable a focusing. The microscopetube has the reference number 36 in FIG. 2.

With the illumination unit described above, the in-situ microscopedevice is used for transillumination bright-field microscopy.Alternatively, an illumination can be provided which facilitates adirect-light darkfield microscopy. Such illumination can be realizede.g. by the presence outside the dip tube of an external light source,the light from which is coupled into light guides which, within themicroscope external tube, are guided inwards to the lens end and guidedthrough a mounting ring encompassing the lens. The light-radiatingend-surfaces of the light guides are aligned at the mounting ring suchthat the radiated light is directed obliquely onto the slide glass bodywith the result that no direct or reflected light, but only lightscattered by the measuring objects, enters the lens, as is necessary inthe case of darkfield microscopy. Alternatively, the light-radiatingend-surfaces of the light guides can be set with their angles ofradiation such that the emerging light evenly illuminates the field ofview, as is necessary for direct-light bright-field illumination.Furthermore, by providing a monochromatic light source and a blockingfilter in front of the camera, an epi-fluorescence illumination can alsobe achieved in the direct light.

What is claimed is:
 1. In-situ microscope device for reactors, with adip tube which is insertable into a reactor connection port and has aninlet, in the end-section pointing to the inside of the reactor, for aspecimen zone, and a microscope external tube, arranged coaxially in thedip tube, which at the inner end is directed with a lens towards thespecimen zone which lies between a lens cover glass and a slide glassbody lying opposite in the dip tube, and at the opposite end is coupledwith a camera, lying outside the dip tube, for photographing the imageof the specimen zone, the lens cover glass and the slide glass bodybeing movable relative to each other, in order to be able to open andclose the specimen zone, characterized in that connected outside to thereactor connection port (6) is a rinsing chamber (7) with sealableopenings (8) through which cleaning agents can be fed in, and the diptube (2) is movable in axial direction in the connection port (6) andcan be pulled back until the inlet (4) communicates with the rinsingchamber (7) in order to be able to clean the specimen zone, sealingmeans (9, 9′) being provided at the dip tube in order to keep theinternal space of the reactor sealed off from the rinsing chamber (7) ifthe dip tube is pulled back to the rinsing chamber.
 2. In-situmicroscope device according to claim 1, characterized in that therelies, at the end of the dip tube pointing to the inside of the reactor,an illumination unit which carries the slide glass body and has a lightsource in order to illuminate the specimen zone through the slide glassbody.
 3. In-situ microscope device according to claim 2, characterizedin that there is arranged in the dip tube (2) a microscope-housing tube(20) housing the microscope external tube (10), wherein themicroscope-housing tube (20) is closed at the end facing the inside ofthe reactor except for an inlet for specimen material and surrounds thespecimen zone from the rear, and wherein the illumination unit isarranged at the inward-lying end of the microscope-housing tube (20). 4.In-situ microscope device according to claim 3, characterized in thatthe microscope external tube (10) is housed movable in axial directionin the microscope-housing tube (20) and a drive (30) is provided whichacts on the end, lying outside the reactor, of the microscope externaltube (10) in order to move this relative to the microscope-housing tube(20) with the result that the specimen zone (12) can be closed andopened between the lens cover glass (14) and the slide glass body (16)of the illumination unit by pushing forward and pulling back themicroscope external tube (10).
 5. In-situ microscope device according toclaim 3, characterized in that the illumination unit is housed movablein axial direction in the microscope-housing tube (20) and, below theillumination unit, a drive is provided in the microscope-housing tube(20), with the result that the specimen zone (12) between the lens coverglass (14) and the slide glass body (16) can be closed and opened bymoving the illumination unit.
 6. In-situ microscope device according toclaim 2, characterized in that the illumination unit is detachablyattached as a separate unit to the base of the dip tube (2), themicroscope external tube (10) is housed movable in axial directiondirectly in the dip tube (2) and a drive (30) is provided which acts onthe end, lying outside the reactor, of the microscope external tube (10)in order to move this relative to the dip tube (2), with the result thatthe specimen zone (12) between the lens cover glass (14) and the slideglass body (16) of the illumination unit can be closed and opened bypushing forward and pulling back the microscope external tube (10). 7.In-situ microscope device according to claim 4, characterized in thatthe drive comprises a step motor or a regulated direct-current motor. 8.In-situ microscope device according to claim 6, characterized in that amagnet is provided which keeps the illumination unit detachable at thebase of the dip tube (2).
 9. In-situ microscope device according toclaim 8, characterized in that the illumination unit has a push button(19) which is arranged such that, when closing the specimen zone, it istriggered by the moving of the microscope external tube up against theillumination unit in order to switch on a light.
 10. In-situ microscopedevice according to claim 6, characterized in that the illumination unitat the end of the slide glass body does not completely fill thecross-section area of the dip tube, with the result that theillumination unit can be grasped from above by a tool in order to removeit from the dip tube.
 11. In-situ microscope device according to claim1, characterized in that a microscope tube is housed movable in themicroscope external tube and a drive means is provided in order to movethe microscope tube in longitudinal direction in a controlled manner, inorder to be able to set the lens against the microscope tube relative tothe specimen zone for focusing.
 12. In-situ microscope device accordingto claim 1, characterized in that the slide glass body has a sapphireglass plate with a level outer surface on which on the circumference anannular rim of a predefined thickness is formed, which serves as aspacer if the lens cover glass is moved up against the annular rim, inorder to close the specimen zone.
 13. In-situ microscope deviceaccording to claim 12, characterized in that the annular rim is formedby the polishing in of a recess into a sapphire glass plate.
 14. In-situmicroscope device according to claim 12, characterized in that theannular rim (32) is formed by applying an annular material layer. 15.In-situ microscope device according to claim 1, characterized in thatthe slide glass body has a sapphire glass plate with a level externalarea on which a plurality of spacers of the same, predefined thicknessis formed which serve as spacers if the lens cover glass is moved upagainst the slide glass body until it rests against the spacers in orderto close the specimen zone.
 16. In-situ microscope device according toclaim 15, characterized in that the slide glass body (16) has on theouter surface two spacers (34) which between them form a channel-shapedrecess open on both sides.
 17. In-situ microscope device according toclaim 2, characterized in that the illumination unit comprises alight-emitting diode as a light source.
 18. In-situ microscope deviceaccording to claim 1, characterized in that, to operate the microscopefor direct-light darkfield microscopy, an external light source arrangedoutside the dip tube as well as light guides are provided, which arearranged such that they receive light from the light source and guide itto a mounting ring, encompassing the lens, from which theirlight-radiating end-surfaces project, in order to direct the emerginglight onto the surface of the slide glass body in such a way that nodirect or reflected light, but only light scattered by the measuringobjects in the specimen zone, enters the lens.
 19. In-situ microscopedevice according to claim 1, characterized in that, to operate themicroscope for direct-light bright-field microscopy, an external lightsource arranged outside the dip tube as well as light guides areprovided, which are arranged such that they receive light from the lightsource and guide it to a mounting ring, encompassing the lens, fromwhich their light-radiating end-surfaces protect, the angle of radiationbeing chosen such that the emerging light evenly illuminates the fieldof view, as is necessary for direct-light bright-field illumination. 20.In-situ microscope device according to claim 19, characterized in that amonochromatic light source is used and a blocking filter is arranged infront of the camera in order to enable an epi-fluorescence illuminationin the direct light.